Abstract
PURPOSE: Emerging evidence suggests that short sleep duration and delayed sleep timing may be independently related to insulin resistance (IR), although findings are mixed. Our aim was to investigate associations between sleep duration and timing with insulin resistance among adolescents. METHODS: The analytic sample included 384 Mexican adolescents from a birth cohort study who took part in a follow-up study beginning in 2015. Insulin and glucose were measured in fasting serum, and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was calculated (marker of insulin resistance; [insulin x glucose]/22.5). Sleep duration and midpoint were measured by actigraphy for 7 days after the visit and for analysis were separated by weekdays and weekends. In full and sex-stratified regression analysis, sleep duration and midpoint were exposures, and the log HOMA-IR was the outcome, adjusting for age. RESULTS: The mean age of the sample was 13.8 ± 1.93 with 51% female. Shorter sleep duration on weekdays was associated with higher log HOMA-IR (β = -.049, 95% confidence interval [CI] -.097 to -.0009). Later midpoints on weekdays and the weekend were independently associated with higher log HOMA-IR (β = .0408, 95% CI -.0049 to .087, and β = .0486, 95% CI .0042 to .093, respectively). Girls showed stronger associations than boys for both sleep duration and timing with HOMA-IR. CONCLUSIONS: Sleep duration and sleep timing were independently associated with insulin resistance, and associations were more pronounced among girls.